Electrofusion and electroporation of cells involves application of an electrical current to the cells. In many instances, it is desirable to align cells prior to applying a direct electrical current. Alignment of cells may be carried out manually by aspiration or vacuum suction. Alignment of cells may also be performed by applying an alternate electrical current. However, when alignment is performed by applying alternate current, cell survival is drastically reduced. Therefore, it would be desirable to have a tool that has a dual capacity to manually align cells and deliver a direct electrical current.
Cell fusion procedure involves localized reversible permeabilization of the cell membrane, which can be induced by applying a pulse or pulses of direct current (DC). It is well known when electrofusing cells, that application of the dielectrophoretic alternating current (AC) for cell alignment prior to administration of the DC pulse greatly improved the rate of cell fusion. The application of AC is necessary for alignment and orientation of the cells in relation to the medium's volume and the distance between the two electrodes. The AC, however, is also known to be deleterious to the cell and at high voltage and/or extensive periods of time is even responsible for cell lysis. Moreover, the typical construction of the chamber is designed so that a large number of cells can be fused at one time. Because of the large volume of medium needed, specific low conductivity solutions are required whose antioxidant components can also harm the cell or, in the specific case of the oocyte, even induce cell activation. An alternative to the existing chamber approach, to avoid the use of antioxidants and the AC at once, is to execute the individual cell alignment manually under dissecting microscopy.
In summary, for conventional electrofusion methods, the disadvantages can be summarized in the requirement for: i) a non-electrolyte solution that is obviously not physiological and can impair cell viability; ii) due to the large inter-electrode distance, the passage of AC pulses can induce thermal damage with consequent cell distress; iii) individual cell alignment is time-consuming; and iv) the electric chamber can be a source of pathogenic contamination due to its repetitive use.
The present invention is directed to overcoming these and other deficiencies in the art.